Perfluorinated linear polyethers having reactive terminal groups at both ends of the chain and process for the preparation thereof

ABSTRACT

AT LEAST ONE OF THE LATTER TWO TERMINAL GROUPS BEING PRESENT WHEN-C6F6O- REPEATING UNITS ARE PRESENT, WITH THE FURTHER PROVISO THAT WHEN SAID -CF2CO-CF3 TERMINAL GROUP IS PRESENT, ONE SAID OTHER TWO TERMINAL GROUPS IS ALSO PRESENT, AND THE CORRESPONDING ACYL HALIDES, LOWER ALKYL ESTERS AND METAL SATLS.   -CF2-COOH, -C(-CF3)-COOH, -CF2-CO-CF3   TERMINAL GROUP BONDED TO SAID CHAIN THROUGH AN ETHER OXYGEN, SAID POLYETHER HAVING TERMINAL GROUPS BONDED TO SAID CHAIN THROUGH AN ETHER OXYGEN, SAID TERMINAL GROUPS BEING SELECTED FROM THE GROUP CONSISTING OF   -CF2-CO-CF3   1. BIFUNCTIONAL PERFLUORINATED POLYETHERS AND MIXTURES THEREOF, HAVING CHEMICALLY REACTIVE TERMINAL GROUPS AT BOTH ENDS OF THE CHAIN, SAID POLYETHER HAVING 1 FROM 1 TO 100 REPEAING UNITS SELECTED FROM THE GROUP CONSISTING OF -C3F6O-, -C2F4O-, AND -CF2O-, WHREIN C2F6 AND C2F4 ARE PERFLUOROALKYLENE UNITS DERIVED FROM THE OPENING OF THE DOUBLE BOND OF A HEXAFLUOROPROPYLENE AND OF A TETRAFLUOROETHYLENE MOLECULE, RESPECTIVELY, THE DIFFERENT OXYPERFLUOROALKYLENE UNITS HAVING A RANDOM DISTRIBUTION ALONG THE CHAIN, THERE BEING NO MORE THAN 50 OFF ANY ONE OF SAID SPECIES OF REPATING UNITS, SAID -CF2OREPEATING UNITS BEING PRESENT ONLY WHEN EITHER OR BOTH OF SAID -C2FF4O- AND C3F6O- REPEATING UNITS ARE PRESENT, SAID -C2F4O -UNITS BEING PRESENT ONLY WHEN SAID -CF2O- UNITS ARE ALSO PRESENT, SAID C3F6O- UNITS BEING PRESENT ONLY WHEN EITHER SAID -CF2O- UNITS ARE ALSO PRESENT OR WHEN SAID POLYETHER CONTAINS A

United States Patent 3,847,978 PERFLUORINATED LINEAR POLYETHERS HAV- INGREACTIVE TERMINAL GROUPS AT BOTH ENDS OF THE CHAIN AND PROCESS FOR THEPREPARATION THEREOF Dario Sianesi and Gerardo Caporiccio, Milan, andDomenico Mensi, Breno, Italy, assignors to Montecatini Edison S.p.A.,Milan, Italy No Drawing. Continuation-impart of abandoned applicationSer. No. 787,309, Dec. 26, 1968. This application June 18, 1969, Ser.No. 834,486

Claims priority, application Italy, July 1, 1968, 817,809/68 Int. Cl.C07c 59/22 US. Cl. 260-535 H 25 Claims ABSTRACT OF THE DISCLOSUREBifunctional perfluorinated linear polyethers having chemically reactiveterminal groups at each chain terminal and no peroxidic oxygen in thechain are obtained from per-fluorinated linear polyethers containingperoxidic oxygen bridges, by chain cleavage at the peroxidic oxygensites, by reacting the peroxidic oxygen-containing polyethers with areducing agent at temperatures of about 30 C. to +250 C. under pressuresof about 1 to 200 atmospheres.

CROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of our application Ser. No. 787,309, filed Dec. 26,1968, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to a new class of perfiuorinated linear polyetherswith reactive functions at both ends of the chain and to a process forthe preparation thereof.

2. Description of the Prior Art In prior patent applications, includingapplications Ser. Nos. 446,292, filed Apr. 7, 1965, now US. Pat. No.3,442,942 issued May 6, 1969; 576,846, filed Sept. 2, 1966 now US. Pat.No. 3,450,611, issued June 17, 1969; 650,257, filed June 30, 1967, nowabandoned; 651,128, filed July 5, 1967, now US. Pat. No. 3,513,203,issued May 19, 1970; 702,533, filed Feb. 2, 1968; and 718,223, filedApr. 2, 1968, now US. Pat. No. 3,665,041, issued May 23, 1972, all ofwhich are assigned to the assignee hereof, there have been describedperfluorinated linear polyethers and copolyethers and mixtures thereofcharacterized by a very high molecular weight, by containing peroxidicgroups and by having at both ends or terminals of the chain either twofunctional groups, or one functional and one neutral group, or twoneutral groups.

SUMMARY OF THE INVENTION We have now discovered that it is possible toconvert these products into new polyethers, including copolyethers, of alower molecular weight and into mixtures thereof, which new products donot contain peroxidic groups and have functional groups at both ends ofthe chain.

Thus, the present invention provides a new class of bifunctionalperfluorinated linear polyethers and copolyethers and mixtures thereof,characterized by having chemically reactive functions at both ends ofthe chain and having the general formula:

Patented Nov. 12, 1974 and CF COCF the last two being possible only whenm is different from zero, and their corresponding acyl halides, esters,amides, nitriles, salts, ketone hydrates and hemiketals.

The present invention also provides a process for the preparation of theabove new products, as well as products in which the three indices m, nand I can be simultaneously zero, and mixtures thereof. This processinvolves cleavage, with reducing agents, of a linear perfluorinatedpolyether (or copolyether) containing peroxidic oxygen and, optionally,subsequent treatments of the reduction products. More particularly, theprocess of the present invention comprises the cleavage of aperfluorinated linear polyether, containing peroxidic oxygen bridges, ora mixture thereof, having the general formula:

wherein the different oxyperfluoroalkylene units are randomlydistributed along the chain; X and Y are the same or different from eachother and are selected from the group consisting of and the derivativesthereof obtained by hydrolysis, salt formation, or esterification of theacid fluoride groups and by addition of water or alcohols to the ketonegroups; -(O)- is an oxygen atom distributed at random along the chainand linked in the peroxidic form to the differcnt oxyperfluoroalkyleneunits; the indices p, q, and r are whole numbers from 0 to 100 with thelimitation that (p+r) is always diiferent from zero and that the sum(p+q+r) has a value between about 10 and 100 or even higher; s is anumber from 1 to the ratio s/ (p+q+r) is between about 0.01 and 0.9, andpreferably between 0.1 and 0.5, and the value of the expression (p+r) sis always greater than zero, said cleavage being carried out .byreacting the above defined polyether or a mixture of such polyetherswith a reducing agent at a temperature of from about 30 C. to 250 C.,preferably from about 20 C. to C., under pressures between about 1 and200 atm., preferably between 1 and 100 atm., optionally in the presenceof a solvent or of a dispersing agent, said reducing agent beingselected from the group consisting of molecular hydrogen, nascenthydrogen, primary and secondary alcohols such as methanol, ethanol,isopropanol, etc., either alone or in the presence of aluminumalcoholates, such as aluminum isopropylate or the like, simple hydrides,e.g. LiH, KH and All-I boron and aluminum complex hydrides such asLiAlH, or NaBH sulfur doixide, hydrogen sulfide and alkali metal saltsthereof, hydrazine, hydroxylamine, phosphorous acid, hypophosphorousacid and the alkali metal salts of phosphorous acid and hypophosphorousacid, stannous chloride and hydroiodic acid.

Optionally, the reduction products may be subjected to furthertreatments of hydrolysis, salt formation, esterification or arnidationof the acid groups, dehydration of amides to nitriles, and addition ofwater or alcohols or amines to the CF COCF ketone groups, to obtain thedesired terminal groups.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The process of this inventioncan be conducted both in the absence as well as in the presence ofsolvent or dispersing liquid media which are inert with respect to thereactants used and to the terminal groups that are formed.

Examples of inert solvents and dispersing agents which may be employedin the process of the present invention are hydrocarbons, desirablycontaining from about 5 to 20 carbon atoms; chlorinated hydrocarbons,desirably containing from about 1 (eg tetrachloromethane) to 5 carbonatoms; chlorofluorinated hydrocarbons, desirably containing from about 1to 5 carbon. atoms; preferably fluorinated and perfluorinatedhydrocanbons, desirably containing from about 5 to 20 carbon atoms;linear and cyclic ethers, such as diethyl ether, tetrahydrofurane,dioxane, etc.; perfluorinated ethers, such as perfluoropropylpiran, etc.

The bifunctional polyethers (including copolyethers) AO(C F O) (CF O)--(C F O) B of the present invention and their mixtures can be separatedfrom other possible reaction products or by-products, such as HF oralkali metal fluoride, in the reaction mixture by conventional methods,e.g., distillation, evaporative distillation, salt formation,filtration, or the like.

The reaction with reducing agents in the process of this inventioncauses a cleavage of the peroxidic bridges present in the chains of thestarting compounds. More particularly, there occurs a cleavage of theoxygen-tooxygen bond with the consequential cleavage of the chain of thestarting polyether at the sites of the peroxidic bridges present in themacromolecule, thus resulting in shorter molecular chains which containat both end-s chemically reactive functions-the products of the presentinvention.

The reducing agents that cause the above mentioned cleavage belong, moreparticularly, to the following classes:

1. Molecular hydrogen, which is preferably employed in the presence ofcatalysts such as palladium, platinum or Raney-nickel, either in finelysubdivided form or supported on carbon or on aluminum oxide, in thepresence or absence of liquid solvent or dispersing media such asalcohols, ethers, hydrocarbons, and halogenated hydrocarbons, preferablyperfluorinated hydrocanbons. The reaction can conveniently be carriedout at temperatures between about C. and 200 C., preferably betweenabout 20 C. and 100 C., and under hydrogen pressures between about 1 and200 atmospheres, preferably between 5 and 100 atmospheres.

2. Nascent hydrogen, that is, hydrogen directly produced in the reactionzone by the action of alkali or alkaline earth metals in aliphaticalcohols or of their amalgams in water or aliphatic alcohols or by theaction of electro-positi-ve metals (such as Zn, Al, Sn, Fe) in inorganicacids or inorganic bases. A particularly useful reducing system of thistype is, for instance, activated zinc suspended in acetic acid, attemperatures between about 50 C. and 120 C., under substantiallyatmospheric pressure.

3. Primary or secondary alcohols of the aliphatic series, alone or inthe presence of aluminum alcoholates. Alcohols suitable for the purposeinclude, for instance, methyl alcohol, propyl alcohol and ethyl alcohol.A particularly suitable reducing agent of this class is isopropylalcohol in the presence of aluminum isopropylate. The reduction of theperoxidic polyether with this class of reducing agents is preferablyconducted at temperatures between about 50 and 120 C. and underatmospheric or slightly greater than atmospheric pressure.

4. Simple or complex hydrides, such as, for instance, LiH, LiBH4, NaBHLiAlH boron hydride and alkylboron hydrides, preferably at reactiontemperatures between about 30 C. and 150 C., in the presence of asuspending medium such as ethyl ether, or 1,2-dimethoxyethane, or evenwater in the case NaBH.,.

5. Elements (or derivatives thereof) of Groups IV, V, VI-A and VIII ofthe Periodic Chart of the Elements published by Fisher ScientificCompany, in their lower oxidation state. Examples of such derivativesare: S0 and H 5 and their alkali metal salts, even in aqueous solution,preferably employed at a reaction temperature between about 30 and 200C. and under pressures between about 1 and 25 atmospheres; hydrazine andhydroxylamine in anhydrous or aqueous alcoholic medium; phosphorous orhypophosphorous acid or their alkaline salts in aqueous solution;stannous chloride in aqueous solution, also in the presence ofhydrochloric acid or ammonium chloride or caustic alkali. Examples ofsuch elements are: iron and tin, desirably in the presence of an acidsuch as HF, HI, HCl, HBr, H and the like.

6. Hydroiodic acid, including aqueous or organic solutions of the alkalimetal salts thereof, in the presence of organic and inorganic acids, attemperatures between about room temperature (22 C.) and C., underatmospheric or slightly greater than atmospheric pressure.

It must be noted that the reduction treatments based on the use of boronand aluminum hydrides, or in which hydrogen is developed in situ by theaction of electropositive metals in protogenic solvents, are preferablyconducted in such a way as to supply the stoichiometric quantity ofreducing agent in ratio to the amount of peroxidic groups to be reduced,so as to prevent possible undesired chemical reductions of the carbonylfunctions of the terminal groups of the products.

The polyethers and copolyethers containing peroxidic bonds that are usedas starting materials in the process of the present invention may beobtained through already described methods, such as those hereinbeforementioned, which are based on the reaction, prevailingly activated by aphotochemical process, of oxygen with tetrafiuoroethylene or withhexafluoropropylene or with a mixture of the two fiuoroolefins.

Among these starting materials, those which we have found to beparticularly useful in the process of the present invention, include,for instance, the polyperoxidic polyethers of high molecular weight,which are obtained by photochemical reaction at low temperature (i.e.below -30 C.) of oxygen with hexafluoropropylene in liquid phase. Theyhave the following general formula:

(5F. AF.

in which the ratio between peroxidic bridges and ether bridges (whichare randomly distributed along the chain), that is the ratio s/(ps), canbe varied on the basis of a suitable choice of the parameters of thereaction (i.e.: radiation intensity of UV rays, temperature, degree ofconversion, etc.) within the preferred range of from 0.1 to 1.

As is described in US. Patent Application Ser. No. 650,257, filed June30, 1967, by conducting the same reaction at higher temperatures, forinstance higher than -30 C., diiferent perfluoroalkylene units, havingthe structure CF can be introduced into the above peroxidic polyethersso that the average formula of the products becomes:

wherein the ratio q/p may vary between about 0.01 and 5.

By analogous photooxidation reactions on mixtures of hexafluoropropyleneand tetrafiuoroethylene, there may be prepared suitable startingperoxidic copolyethers also containing variable contents of -CF -CFperfiuoroalkylene units, that is, copolyethers having the structure:

wherein the ratio r/ p may be, for instance, between about 0.1 and 10and the ratio of q/(p-i-r) may be between about 0.01 and 5.

In US. Patent Application Ser. No. 702,533, filed Feb. 2, 1968, therehave also been described photooxidation reactions of onlytetrafiuoroethylene dissolved in an inert solvent whereby there areprepared the starting peroxidic copolyethers of the formula:

wherein the ratio of g/r can vary, for instance, within the range offrom about 0.2 to 5, the ratio of s/(q-i-r) can be between about 0.1 and0.5, still having, however, the difference r-s greater than 0, and X andY can be the CF -COF or CF COF groups.

All of these products are within the foregoing general formula definingthe starting materails used in the process of this invention.

In addition, the following products, also within said general formulaand having the formula:

with X and Y selected from the CF COF and -CF COF terminal groups, andhaving a ratio s/ (r-s) between about 0.2 and 5, are prepared throughthe direct reaction of tetrafluoroethylene with oxygen under more thanatmospheric pressure, by such procedures as, for instance, thosereported by A. Pajaczowski and J. W. Spoots in Chem. Ind. 1964, p. 659;F. Gozzo & G. Carraro in Nature, 206, 507 (1965).

The action of the above defined reducing agents on the peroxidicpolyethers and copolyethers causes, as was explained before, thecleavage of the OO bonds present in the chains, according to reactionsthat can, for example, be schematized by the following equations, inwhich the symbols P and P represent perfiuorinated polyether chains ofany arbitrary length and structure within the foregoing definitions ofthe starting materials.

The rupture of the starting macromolecule at the site of each of theperoxide bridges (s) causes the formation of a mixture made up of (s,+l)molecules of perfiuorinated polyethers of lower molecular weight thanthe starting polyether, and containing at least (s-1) molecules which atboth ends have chemically reactive functions, such as the ketone andcarboxylic acid functions. (As shown in the last of the above indicatedreactions, chemical functions of the fluoroformate -OCOF type can formfollowing the rupture of a peroxidic bond adjacent to one -CF O unit; inthis case, given the known instability of said funtcion, there must beexpected either in the reaction medium itself or during the subsequenttreatment of the products, the elimination of COF and the formation of anew end group with a carboxylic or ketonic function depending on thesubsequent perfiuoroalkylene unit).

As illustrated below, the rupture of the peroxidic linkages causes theformation of polyether chains with acid fluoride groups at both endswhen the starting peroxypolyether macromolecule contains only CF CFperfluoroalkylene units whereas there are formed polyether chainscontaining an acid fluoride group at one end and a ketonic group at theother end when the starting peroxypolyether macromolecule contains onlyIt will be understood, as previously mentioned, that the terminal groupsof the products actually obtainable by the reduction reaction can bedifferent from those indicated above, namely That is, they can be thederivatives of these groups obtained by hydrolysis, esterification,hydration and salt formation with various reactants or solvents presentin the reaction medium or used in the course of the processing of theproducts.

The average molecular weight of the perfiuorinated polyethers withreactive functions at both ends, thus 0 tained, depends essentially onthe concentration of peroxidic groups of the starting polyether. Moreprecisely, the greater this concentration, the lower the molecularweight of the difunctional polyethers. As an order of magnitude, withreference to the general formulae reported before, the average value ofthe sum (m+n+l) in the bifuncti-onal polyethers of the presentinvention, obtained by the process of this invention, is the same as theratio which characterizes the starting peroxidic materials. The averagemolecular weight of the bifunctional polyethers can be less than thatvalue when oxydifluoromethylene -CF O units adjacent to peroxidicbridges are present in great numbers in the starting product.

Considering the fact that the distribution of the perox idic bridges andof the ether bridges in the molecules of the starting materials is of asubstantially random nature, it follows that the break up of saidperoxidic bridges produces a mixture of *bifunctional polyethers havingdifierent chain lengths.

For instance, by subjecting to reducing cleavage a mixture of peroxidicpolyethers having the structure that is CF; M OF, there is obtained asthe main reaction product (for instance after hydrolysis) a mixture ofpolyethers with acid and ketone terminal groups having the generalformula:

In the reaction mixture are present various members of the seriescharacterized by a precise value of the index m'(0, l, 2, 3, 4,), andthe average of m characterizing this mixture approximates the ratio(p-2s)/ (s+1). In the reaction mixture are also present polyethershaving at one end of the chain one of the original end groups (X, Y).The molar concentration of these latter products tends to the value of2/ (s+l) and decreases with increasing molecular weight and peroxidicbridge content of the initial polyperoxide-polyether.

-In the event that the starting polyether contains more than one type ofperfluoroalkylene unit, the bifunctional products obtained by theprocess of the present invention, in addition to the molecular weightdistribution discussed above, will also have a structural orcompositional distribution as discussed below.

For instance, the reducing cleavage of a product of the average formula:

after hydrolysis of the acyl fluoride groups, gives a mixture ofbicarboxylic acids of the general formula:

having an average degree of polymerization (n+1) the same as or onlyslightly less than the value of with an average ratio n/ (l+2) the sameas or only slightly lower than the ratio q/r of the starting product.The mixture contains bicarboxylic polyethers of different molecularweight or polyethers of the same degree of polymerization, (n+1), butcharacterized by a different chemical composition, that is, by adifferent ratio n/l, or also polyethers of identical general formula butisomeric amongst themselves, due to a difl'erent (random) distributionof the two perfluoroalkylene units along the chain.

For example, 'by treating, in accordance with the present invention,mixtures of peroxid'ic c-opolye-thers of the formula: X-'O( OF O C F O)-Y characterized by ratios s/'(q+rs) of the order of 0.3, -by ratios r/qaround 1.5 and by average molecular weights around 10,000 (q-l-r) 100)one obtains, after hydroylsi's, mixtures in which are present thefollowing bicarboxylic acids:

8 HOOCCF O-(CF O) CF --CF -O-CF COOH (2,4,6,9tetraoxaperfluorodecan-l,10-dicarboxylic acid) (JR-COOH 2,4,7,9tetr-aoxaperfiuorodecan-1,10-dicarboxylic acid)HOOCCFZO-CF2O-(CFg-CFFO)2-CF2- COOH(2,4,7,lO-tetraoxaperfiuoroundecan-l,1l-dicarboxylic acid) HOOCCF -OCF-O (CF CF 0) CF COOH (2,4,7,10-tetraoxaperfluoroundec-an-ll'l-dicar-*boxylic acid) HOOCCF OCF CF ,OCF -OCF OF -OOF COOH (2,5,7, 10-tetraoxaperfiuoroun decan-l,l l-d'icarboxylic acid) H0O C CF O-(OF CF-O 3C'F2COOH (2,

5, 8,1 1-tetraoxaperfluorododecan-1,12-dicarboxylic acid) four isomericbicarboxylic acids, HOOCCF -O-- CF 0 -(CF -CF O) -CF -COOH (isomericreferring to the distribution of the two CF O units and the two CF -C FO- units along the chain); HOOCCF -O'(CF C-F 0) CF COOH '(2,

5,8,11,14 pentaoxaperfluoropentadec-an-1,15-dicarboxylic acid) andbicarboxylic acids of similar structure but of greater molecular weight.

1 The ditferent bifunctional polyethers obtainable by the process hereindescribed can be isolated in the pure state from the mixtures containingthem by using conventional techniques, such as for instance:distillation, vapor phase or liquid phase chromatography, selectiveextraction with solvents, etc., either by operating directly on thereaction product or after suitable treatments for chemically modifyingthe reactive end groups (i.e.: esterification, saltformation, amidationof the carboxylic groups, formation of acyl halides, formation ofaddition compounds of ketone groups with water, alcohols or amines,etc.).

For many of the possible applications it is not necessary, however, touse compounds of this type in the pure state, but it is possible to usethem in mixture characterized, for instance, by a more or less limiteddistribution of molecular weights and of composition.

It must be noted that the described bifunctional polyethers can befurther transformed into a great number of derivatives, by recourse totypical reactions of both the carboxylic acid groups and the ketonegroups. Among these latter reactions can be mentioned, for instance, thereaction with aqueous bases according to the following scheme:

by which reaction the terminal ketone function is transformed into aneutral and stable group CF H or into a carboxylic acid CF -COOH group.

The bifunctional polyethers of the present invention with chemicallyreactive functions at both ends, find a direct use in the synthesis ofpolycondensation polymers. Such polymers (polyesters, polyarnides,polyimides, etc.) have particularly desirable characteristics of heatresistance and stability to solvents, owing to the presence of fluorinein their molecules. For instance, polymers such as the polyamide ofExample 14 may be formed into self supporting films that are stable tosolvents, light, oxygen, and heat.

Moreover, such polymers exhibit the highly desirable characteristic offlexibility at very low temperatures, e.g., as low as of the order of(3., due to the presence of ether bridges in the chain.

In addition, many of the bifunctional polyethers exert an importantaction on the reduction of the surface ten sion of aqueous solutions.They can therefore be used as surface active agents, such as for examplethe acids and ketoacids of Example 1. Other bifunctional polyethers,

especially those containing ester groups and nitrile groups, such as forexample those of Examples 2 and 3, are valuable plasticizers forfluorinated polymers and, being characterized by a very high thermalstability, can be used as heat transfer agents in a wide range oftemperatures.

The bifunctional polyethers, owing to the presence of a chain containingperfiuorinated groups and of reactive chemical functions, can be used asstarting materials for the synthesis of various derivatives useful forimparting oiland water-repellency to fibers, films and textiles.

For the convenience of the reader, some spectroscopic data which areuseful for the determination of the structure of polyethers,copolyethers and mixture thereof, of the type herein described, are setforth below. These data relate to absorptions in the IR spectrum and toresonance bands in the nuclear magnetic resonance (NMR) spectrum whichit is believed can be associated with the presence of given chainterminal groups.

-In the infrared (I.R.) absorption spectrum, the following relationshipscan be considered:

Associated LR.

In the resonance spectrum of fluorine the resonances in the listed zoneshave been associated (by us) with fluorine atoms belonging to thecorresponding terminal groups listed in the last column.

+55 3 OCF-O-CF3 +59 2 -CF2OCF2COF As regards NMR bands associated withthe presence of given perfiuoroalkylenoxy units in the chains, referencemay be had to application Ser. No. 650,257, filed June 30, 1967 and Ser.No. 718,223, filed Apr. 2, 1968.

Set forth below are several examples illustrating the synthesis oftypical starting polyethers for use in process of the present invention.

(A) Preparation of a mixture of polyperoxidic per- !fluoropolyethershaving the formula:

The equipment consisted of a cylindrical reactor of Pyrex glass having adiameter of 80 mm. and a capacity of 1 liter, fitted with 4 necks andprovided with a thermometer, an inlet tube for the introduction of gas,a reflux condenser cooled at -80 C., and a Pyrex finger with an out- 10side diameter of 45 mm. immersed coaxially in the reactor and containingan ultra-violet quartz lamp, original Hanan Q 81.

Into this reactor, thermostatically maintained at a temperature of 45 C.and containing 750* g. of C F in liquid phase, was continuously bubbledthrough an inlet tube reaching the bottom a gaseous mixture mainlyconsisting of O and recycled olefin, while the gaseous mixture comingout from the system through the top of the reflux condenser, cooled atC., after washing in 40% aqueous KOH and after drying on CaCl wasreintegrated with new dry 0 corresponding to the amount reacted, andthen cycled back into the reactor at a flow rate of about 40liters/hour.

After 6 hours of reaction at 45 C.i2 C., with a total consumption of 8liters of 0 measured at ambient conditions, the gaseous products (C Fhexafiuoropropylene oxide, COF CF COF) Were vented off and there wereobtained 75 g. of a viscous perfluoropolyether oil having a compositioncorresponding to the average formula C3F5 97O1 24 with a structure(determined by N.M.R. analysis and iodometric titration of activeoxygen) conforming to the general formula set forth above, wherein X andY are.

COF,CF3,-CF-OGF3,

a and -CF COF groups, the relative proportions being about0.8:1:0.05:0.25, respectively, and in which the average ratio of theindices s/ p is 0.19. By measurement of the number average molecularweight, it was determined that the value of p was between 40 and 45.

(B) Preparation of a mixture of polyperoxidic perflu ropolyethers havingthe formula:

The equipment was exactly the same as that described in Example A exceptthat the finger coaxial to the reactor and holding the U.V.-lamp,Original Hanan Q 81, was made of quartz and had an outside diameter of25 mm.

Into the reactor, thermostatically maintained at -40 C. and containing750 g. of C F in the liquid phase, was continuously bubbled through,with a flow rate of 60 liters/hour, a mixture of C 1 and O in a molarratio of 2: 1, while the gaseous mixture coming out from the system,after passing through a reflux condenser cooled at 80 C., was allowed todisperse.

After 4 hours of reaction, the gases (C F C F epoxides of C F and of C FCOF CF COF) were vented off. 290 1g. of viscous oil were recovered, thisoil having a composition corresponding to the average formula CF O andhaving a structure conforming to the general formula set forth above inwhich X and Y are and CF COF groups in the relative proportion of 0.7:1:001:03, respectively, and wherein the average ratio of the indexes r/pis 1.5, s/(p+r) is 0.09. The average value of (p-l-r) was of the orderof 40, as determined by measurement of number average molecular weight.

(C) Preparation of a mixture of polyperoxidic perfluoropolyethers havingthe formula:

The equipment used for the purpose was identical to that described inExample (B), except that the reactor was built of steel.

Into the reactor, thermostatically maintained at 0 C. and containing1.06 kg. of C F in the liquid phase under 5 atmospheres pressure, therewas continuously introduced through an inlet tube reaching the bottom afiow of compressed dry 0 while at the outlet of the condenser, kept at-80 C., there were regularly vented through a pinvalve 40 liters/hour ofgases substantially consisting of 1 1 oxygen, while maintaining thepressure inside the system constantly at 5 atmospheres.

After 2 hours of reaction, the gases were evaporated and 280 g of aviscous oil were recovered; having the general formula set forth above,wherein X and Y are groups, in the relative proportion of 1:0.6:0.2:0.6,respectively, and having a composition corresponding to the elementalformula 01 with a peroxidic oxygen content of 1.65 g. per 100 g. of oil,an average ratio q/ p of 0.3 and an average value (p-f-q) of the orderof 12.

(D) Preparation of a mixture of polyperoxidic perfluoropolyethers of thefollowing formula:

The apparatus was identical to that employed in Experiment (B).

, Into the reactor, thermostatically maintained at 40 C. and containing600 cc. of liquid CF Cl these were continuously bubbled through an inlettube reaching the bottom a mixture of dry 0 (flow rate 30 liters/hour)and C 1 (at a flow rate of 15 liters/ hour, while the gases flowing outof the system, after passing through the reflux condenser kept at -80"C., were allowed to disperse. At the same time, there was continuouslydrawn from the re actor a solution of polyperoxidic oil dissolved in theCFgClz solvent which latter was then evaporated and recycled. Underthese conditions a production of about 30 g/h of polyperoxidicperfiuoroetheric oil was obtained, which oil was highly viscous and hadan average molecular weight of about 10,000 and a structure in agreementwith the general formula set forth above, wherein X and Y are CF COF andCF COF groups and wherein the average ratio q/ r is 0.3 and the ratio s/(q+r) is 0.25.

(E) Preparation of a mixture of polyperoxidic perfiuoropolyethers of theformula:

Into an autoclave of stainless steel, having a capacity of 200 cc.,provided with a pin-value, containing 100 g. of CF CICFCI and kept at 80C., were introduced by distillation, under vacuum, 20 g. of C F Then 5liters of dry 0 containing 0.1% of ozone were absorbed into this mass.The resulting mixture was then reacted, while allowing the temperatureto rise from -80 C. to 0 C. in hours.

At the end of the reaction, after removal of the dissolved gases, therewas obtained a solution containing 10.5 g. of a peroxidic product havinga. structure in agreement with the above general formula, wherein X andY are CF -COF and CF COF groups, and with an average ratio s/(r-s) of1.5.

(F) Preparation of a mixture of peroxidic perfluoropolyethers having thestructure:

A 5.3 liter stainless steel reactor having a cooling jacket and an innerdiameter of 12 cm. and being fitted with inlet pipes reaching the bottomof the reactor for feeding the reacting gaseous mixture and the solvent,and the outlet pipes for the continuous drawing off of the liquidreaction mixture was used. A quartz sheath with an outside diameter of Scm., in which was inserted a mercury-vapor lamp of 900 W of the Hanan TQ 1200 type, was placed at the center of the reactor. The gases leavingthe reactor were cooled in a reflux condenser at 78 C. The reactor wasfilled at 35 C. with liquid CF Cl and a gaseous mixture of 150 l./hr. ofC 1 and 250 l./hr. of oxygen was continuously fed into the reactor. Thereaction mixture was irradiated for 3 hours at 35 C. Thereafter, thereaction mixture was continually drawn oif and the CF Cl solvent thereinwas removed by evaporation at 80 C. and recycled back to the reactor.The draw 01f ratio was about 250 g./hr. of recovered reaction product(without solvent) in the form of a viscous and non-volatile liquid.

The reaction was continued until 20 kg. of product was obtained. Duringthis period the gases leaving the reflux condenser, consisting primarilyof COF tetrafluoroethylene epoxide, unconverted tetrafiuoroethylene,unconverted oxygen and CF CI were eliminated by washing with a 15% KOHsolution. Iodometric analysis of the product showed 2.1 g./100 ofperoxidic oxygen. The N.M.R. spectrum showed that the product consistingof --CF units and CF CF units distributed randomly and linked to eachother by ether bridges or by peroxidic groups.

The C F /CF ratio was about 0.8. However, because of high molecularweight, N.M.R. analysis could not detect the presence or the structureof the end groups (perfluoroalkyl, acyl fluorides, fluoroformyl groups).The structure of the product, except for the nature of the end groups Xand Y, can thus be indicated by the formula: X-0(C F O),(CF O) (O) --Y,wherein the value of the sum r-l-q is considerably greater than 100; r/qis about 0.8 and s/(r-i-q) is 0.116.

(G) Preparation of a mixture of peroxidic perfluoropolyethers having thestructure:

Example F was repeated except that the reactor was filled with liquid CFCl at -50 C. and that the reaction mixture consisting of a continuouslyfed gaseous mixture.

of 150 l./h. of C F and 300 l./h. of oxygen was irradiated for 68 hoursat a temperature between -50 C. and 55 C. At the end, after the removalby evaporation at C. of the gases and of the CF Cl solvent therein, 7.5kg. of residual product were obtained.

The N.M.R. spectrum showed that the product consisted of the CF CF andCF units distributed randomly and linked to each other by ether bridgesor peroxidic groups, while, because of the high molecular weight, theN.M.R. method could not detect the presence or the structure of endgroups. The C F /CF ratio was about 1.6, while the peroxidic oxygencontent determined by iodometric titration was 2.4 g. of active oxygenper g. of oil.

The structure of the product, except for the nature of the end groups Xand Y, can thus be indicated by the general formula:

wherein X and Y are chain end groups, the sum (r-l-q) is considerablygreater than 100, the ratio r/ q is about 1.6, and the ratio s/ (r-l-q)is about 0.15.

EXAMPLE 1 Reduction by hydrogen of a mixture of polyperoxidicperfluoropolyethers having the general formula:

Into a stainless steel 1 liter autoclave, fitted with a heating mantle,and containing 20 g. of carbon with 0.5% of palladium supported on it,were introduced 470 g. of the product of Example (A). The autoclave wasthen evacuated and thereafter hydrogen was introduced until a pressureof 40 atm. was achieved, at room temperature. The mixture was allowed toreact for 20 hours at 50 C.

At the end of the reaction, the gas, consisting of H COF and CF COF, wasdischarged and the reaction product (400 g.) was separated by filtrationfrom the catalytic residue. The thus obtained crude product of thereduction reaction did not contain peroxidic oxygen and had a viscosityat 20 C. about 30 times lower than that of the starting product. N.M.R.(nuclear magnetic resoanace) analysis of this product revealedthepresence of Fa Fa end groups.

350 g. of the reduced product were then hydrolyzed with 500 cc. of 40%(aqueous) H 50 under agitation for two hours in a 1 liter glass flaskthermostatically maintained at 50 C.

The organic layer was then separated and stirred for 3 hours, at 50 C.,with 40 g. of powdery CaCO in order to form the calcium salts of thecarboxylic groups. The semi-liquid mixture thus obtained was subjectedto dis tillation by heating to 120 C. while applying a vacuum, graduallydecreasing the pressure from 20 mm. Hg to 0.1 mm. Hg.

During this operation there were distilled out about 70 g. of polyetherproducts which were free of carboxylic acid groups.

The saline residue of the distillation was then extracted three timeswith 500 cc. of a mixture of CF ClCFCl,

14 EXAMPLE 2 The polyperoxidic polyether oil of Example 1 was subjectedto reduction by reacting it with an excess of methyl alcohol at thereflux temperature of the alcohol. A sample of 200 g. of said oil wasreacted" with 200 g. of 99.9% methanol at reflux temperature, for 30hours. Thereafter the mixture was poured into a mixture of water and ice(500 g.) and the organic layer was then separated and brought to aconstant weight by evaporation of the residual alcohol at a temperatureof 30 C. and under a vacuum of 20 mm. Hg. The mixture was then treatedwith 98% H 80 at a temperature of C. 150 g. of the residual product thusobtained were subjected to fractional distillation, whereby thefollowing pure compounds were obtained in the amount indicated:

Boiling oint Auto CFa

CFa

and CH CI in a volumetric ratio of 4:1, and then slowly added to 500 cc.of 30% HCl in order to free the carboxylic acids. The organic phase thusfreed was dried with 98% H 80 and then with Na SO Various analyses(N.M.R. spectroscopy, acidimetric titration) showed that the productobtained is a mixture of bifunctional polyethers predominantlycomprising the products of the series:

with an average value of m between 3 and 4.

By fractional distillation of this mixture there was separated the lowerperfluorinated ketoacids, having the boiling temperatures recorded inTable l, in the indicated amounts.

During this distillation there were also separated minor amounts of thefollowing bicarboxylic acids:

(1.5 g; b.p. 99-103 C. at 0.1 mm. Hg.)

(1.0 g; b.p. 120125 C. at 0.1 mm. Hg.)

CFa-CF-O (CaFsOh-CF-CF:

UOOH 0011 (0.5 g; b.p. 135-140" C. at 0.1 mm, Hg.)

TABLE 1 CFaCOCFzO (C:FaO)m-(|3FCOOH 0 Fa Amount Boiling temperature m(E) J 10 188190 C. 9 210-212 C. 5. 5 9598/0.2 mm. Hg.

5 100103/0.1 mm. Hg.

The residue ('80 g.) had an average acid'imetric equivalent weight ofabout 1700 and, by N.M.R. analysis, was found to consist of a mixture ofbifunctional polyethers of the same constitution but greater molecularweight. Samples of the isolated keto-acids and bicarboxylic acids and ofmixtures thereof, as well as of the residual mixture, were found to havethe property of lowering the surface tension of water from 72 dyne/cm.at 20 C. down to -20 dyne/cm. at C., even in concentrations of 0.01%.

EXAMPLE 3 A sample of 50 g. of the same polyperoxidic polyether used asthe starting material inExample 2 was introduced into a 300 cc. glassflask, fitted with a stirrer and a reflux condenser, together with 45cc. of glacial CH COOH and 4.5 g. of powdered activated Zn. Theresulting reaction mixture was stirred for 15 hours at refluxtemperature. Then the acetic acid was extracted with water saturatedwith NaCl, the unreacted excess Zn was then dissolved by adding 25 cc.of 20% H 50 the aqueous layer was then again separated and the organiclayer was diluted with 50 cc. of CF CICFCI and then dried with 98% H Thesolvent was then evaporated and the residue brought to constant weightunder a 1 mm. Hg vacuum at 30 C. Thereby 30 g. of a product free ofperoxidic oxygen were obtained. The reduction product had an equivalentaverage acidimetric weight (PE) of about 1400, as determined by theformula W X 100 PE M wherein W is the weight expressed in grams of thesample, and M represents the numbers of milliters of 0.1 N solution ofNaOH employed for neutralization of the acid groups contained in thesample.

By treating this product with excess S001 at reflux temperature for 3hours, then removing the excess reactant by mechanical separation andsubsequent extraction with benzene, and finally treating the productwith methanol in the presence of anhydrous pyridine, a mixture of estersof the carboxylic acids was obtained. This mixture was separated byrectification into various fractions in which, by gas-chromatography,there were identified the same products identified and described asesters in Example 2.

EXAMPLE 4 A sample of 30 g. of the polyperoxidic polyether oil describedand used as the starting material in Example 1 was dissolved in 100 cc.of anhydrous ethyl ether, and placed in a 500 cc. glass flask fittedwith a stirrer, a reflux condenser and a dropping funnel. To thesolution of the oil, kept under agitation and thermostaticallymaintained at -10 C., was slowly added, within a period of 1 hour, asolution consisting of 0.4 g. of LiAlH in 100 cc. of anhydrous ethylether.

At the end of this operation, 1 cc. of methanol was slowly added withina period of 10 minutes, and the re- EXAMPLE 5 The reduction carried outin Example 4 was repeated under the same conditions, using as thedispersing agent isopropyl alcohol and as the reducing agent equivalentamounts of NaBH Thereby were obtained similar results to those obtainedin Example 4.

EXAMPLE 6 20 g. of peroxidic perfluoropolyether oil, of the samecomposition as that used in Example 1, were introduced into a 50 cc.stainless steel autoclave together with 5 cc. of H 0. To this were thenadded 10 g. of S and the whole mixture was then reacted under agitationfor 30 hours at 100 C. At the end of the reaction, after removal of thegases, the product (15 g.), dried over 98% H 80 and filtered over Na SOshowed practically no peroxide content and appeared to be formed by amixture of polyethers prevailingly corresponding to the general formula:

oFree-oFz0(OaF.0)...-CFCO0H with an average value of m between 3 and 4.

EXAMPLE 7 A sample of 20 g. of the peroxidic perfluoropolyether oildescribed as the starting material in Example 1 was reacted with 1 cc.of hydrazine in the presence of 15 cc. of ethyl ether in a glass flask,at the reflux temperature of the solvent, for 20 hours. At the end ofthe reaction, the mixture was poured into 20% H 80 under steadystirring, and after 5 hours the separated organic layer, after dryingover 98% H 80 and filtering over Na SO and after evaporation of thesolvent, showed no peroxidic oxygen and the same composition as thatfound in the previous examples.

EXAMPLE 8 A sample of 50 g. of peroxidic perfluoropolyether oil, havingthe same characteristics as the starting material used in Example 1, waspoured into a 500 cc. glass flask together with 12 g. of Al(Oi-C H(triisopropoxy aluminum) and 200 cc. of isopropyl alcohol, and themixture was then reacted for 20 hours at reflux temperature. At the endof the reaction, the mixture was poured into an excess of 20% H SO at atemperature of 0 C., and the perfluorinated organic product wasfractionated by following the procedures described in the previousexamples.

This product had an equivalent average acidimetric weight of about 1420,did not show any peroxidic oxygen by iodometric analysis, was and,according to the N.M.R. analysis, formed of a mixture of the productsalready described in the preceding examples.

EXAMPLE 9 Reduction by means of hydroiodic acid of a mixture ofpolyperoxidic perfluoropolyethers of the general formula:

40 g. of an oil prepared as described in Example (B) were dissolved in100 cc. of CF ClCFCl and were then introduced dropwise into a 500 cc.flask equipped with a 16 stirrer and a reflux condenser, containing amixture consisting of cc. of acetic anhydride, 100 cc. of

CF Cl--CFCl and 10 g. of NaI.

This mixture was then reacted for 3 hours, and then was diluted with 100cc. of 10% HCl, and the iodine thus formed was reduced with a stream ofS0 The resulting mixture was poured into a mixture of water and ice (500g.) and the organic layer was then washed with water saturated with S0and thereafter dried over 98% H SO and then over Na SO After evaporationof the solvent, the product appeared to be free of peroxidic oxygen andshowed an equivalent average acidimetric weight of 1330. The N.M.R.analysis revealed that the prevailing terminal groups were-CFzCOCFa,-CF:COOH and CF-COOH,

F: with minor amounts of CF;, groups.

The reduced product was then treated with 5 g. of CaCO in order to formthe calcium salts of the carboxylic acid groups and the mixture was thensubjected to distillation under vacuum at C. and at a pressure of 0.1mm. Hg. The residue, after repeated Washing with a mixture ofCFzCl-CFCLZ and CH Cl in a volume ratio of 4:1, was poured into 50 cc.of 30% HCl in order to free the carboxylic acids from their calciumsalts.

Thereupon the organic layer was separated and dried with 98% H SOthereby obtaining 25 g. of a mixture of bicarboxylic acids and ketoacidswith an average forgroups, the ratio m/l was about 0.6 and the averagevalue (m+l) was between about 6 and 7.

EXAMPLE 10 Reduction by hydrogen of a mixture of polyperoxidicperfluoropolyethers of the general formula:

A sample of 100 g. of an oil, obtained according to the procedure ofExample (C), was introduced into a 200 cc. stainless steel autoclavewhich contained 5 g. of carbon containing 0.5% of palladium, and then 50atm. of hydrogen were introduced and the mixture reacted for 15 hoursunder agitation at 50 C.

After having discharged the gases, the reaction products were pouredinto 200 cc. of 40% sulfuric acid in order to hydrolize the acidfluorides. Then the organic layer was treated with 15 g. of CaCO andsubjected to distillation at from 150 to C. under a vacuum which wasgradually intensified to 0.1 mm. Hg. The saline residue was then washedthrice with 100 cc. of a mixture of and CH Cl (4:1 volume ratio), andthen acidified with 30% HCl. The organic layer was then separated anddried with 98% sulfuric acid and then with Na SO The product thusobtained (40 g.), by N.M.R. analysis and acidimetric titration, wasfound to consist of a mixture of polyethers containing at least onecarboxylic acid terminal group and corresponding to the general formula:

AO-(C F 0)m(CF 'O) B wherein A and B are selected from -OFzCOCF -oF-OOOH, CFCO0H,

and minor amounts of -CF terminal groups, and the average ratio n/m isabout 0.2, while the sum (m+n) is about 3.

17 From this mixture were separated, by fractional distillation and bygas-chromatography of the esterified fractions, among others, thefollowing new bifunctional polyethers:

CF COCF --CF O-CF-COOH b.p.173-175 C.

EXAMPLE 11' Reduction by hydrogen of a mixture of polyperoxidicperfluoropolyethers having the general formula:

A sample of 200 g. of a product obtained as described in Example (D) wasintroduced into a 500 cc. stainless steel autoclave containing 10 g. ofcarbon with 0.5% of palladium, and was thereupon reacted with hydrogenfor 20 hours under agitation at a temperature of 40 C. and under apressure of 40 atm.

A portion of the reduction product, which contained no periodic oxygen,after hydrolysis with 40% sulfuric acid, and drying over 98% H 80 and P0 was found to have an equivalent acidimetric average weight and anN.M.R. analysis in agreement with the average formula:

This mixture, in a concentration of 5 10- moles/ liter, lowered thesurface tension of water from 72 dyne/ cm. down to 18 dyne/cm.

A portion of 15 0 g. of the non-peroxidic reduction product, having withacid fluoride terminal groups, was reacted with a small excess ofanhydrous CH OH and, after removal of the excess of CH OH and HF, acurrent of gaseous diazomethane was bubbled therethrough. The esterifiedmixture thus obtained was fractionated, thus distilling 60% of theproduct into fractions until reaching 150 C./ 0.1 mm. Hg. From some ofthe fractions, by gas-chromatographic separation, the following methylesters were separated:

Boiling Amount point (5) Remarks 2 isomers.

4 isomers.

Another sample of 5 g. of a mixture of acids of the same averageformula:

was treated with SOCl for 3 hours in a reflux condenser, at the end ofwhich treatment the excess SOCl was extracted with benzene and pentane;the end product was found to have undergone a quantitative conversion ofthe carboxylic groups into acyl chloride groups.

EXAMPLE 12 To this were then added 30 cc. of methanol. The mixture wasstirred while slowly adding 30 cc. of 57% hydroiodic acid and was thenrefluxed for 30 minutes. Then the organic layer was separated from theinorganic phase and the organic layer was washed twice with 20 cc. of 5%aqueous KI solution. Thereupon the organic layer was dried with P 0 andthe product (20 g.) was distilled under a vacuum of 0.1 mm. Hg at 150 C.

By gas-chromatography analysis, N.M.R. spectroscopy, and thedetermination of the saponification number of the methyl esters, thereduction product was found to contain, in the form of methyl esters,the bicarboxylic acids, recovered, recognized and described in Example11.

EXAMPLE 13 Reduction by means of hydroiodic acid of a mixture ofpolyperoxidic perfluoropolyethers having the following structure:

A sample of 15 g. of an oil obtained by the procedure described inExample (E), dissolved in 25 cc. of

CFgClCFClg,

was introduced dropwise into a 250 cc. flask fitted with a stirrer and areflux-condenser and containing cc. of acetic anhydride, 100 cc. of CFClCFCl and 20 g. of NaI.

The resulting mixture was reacted at 20 C. for 3 hours and then dilutedwith 50 cc. of 20% HCl. The iodine formed was then reduced with acurrent of S0 Thereupon the mixture was poured into a mixture of waterand ice (500 g.) and the organic layer was separated, washed with asaturated aqueous solution of S0 and then dried with 98% H 80 and thenwith Na SO 5 g. of this product were then esterified with diazomethane.The portion of the product which distilled over at C. under a pressureof 0.1 mm. Hg (80%) was passed through a gas-chromatographic columnwhereby it was possible to isolate suflicient amounts for identificationof the following products:

In aqueous solution, 0.020 g./liter of the acid,

was found to reduce the surface tension of water from 72 dyne/ cm. downto 16 dyne/ cm. at 20 C.

EXAMPLE 14 5 g. of the ketoacid,

were treated in a small 50 cc. flask, fitted with a reflux condenserconnected with a gas buret and a dropping funnel, with 10 ml. of 20%NaOH at a temperature of 50 C. for a period of 2 hours, during which 85cc. of CF H gas, measured under ambient conditions, developed.

The reaction product thus obtained was then acidified with 20 ml. of 35%B01, whereby a heavy organic liquid separated, which liquid wascollected, washed with H O, dried with 98% sulfuric acid and thenfractionated in a microdistiller. At 60 to 65 C. and under a pressure of1 mm. Hg there were collected about 2 g. of a fraction substantiallyconsisting of the compound C FzH-O (CaFaOh-C F-COOH F20 (CaFuO)2C F-O 0Cl 0 Cl F3 was distilled over.

This product was then dissolved in 6 ml. of CH CI and 4 ml. of CFC'l-CFCl and the solution was then introduced into a 100 cc. test tube.Over this liquid phase was carefully placed a solution of 0.190 g. ofhexamethylenediamine dissolved in 32 ml. of 0.1 N NaOH.

On the surface of the two phases a solid white film formed which wasgrasped by tweezer and removed to thereby promote the formation of moresolid product. In

, this way there were obtained about 0.9 g. of a polyamide having theformula:

A 0.12% solution of the product in benzotrifiuoride had an intrinsicviscosity at 80 C. of 0.35/ 100 cc./g., thus showing a value of it above20.

This polymer had a high thermal stability and resistance to oxidationand was practically insoluble in most of the common organic solvents. Afiber of this polymer was recovered unchanged after 10 hours heating inair at a temperature of 250 C.

EXAMPLE Into a stainless steel, 2500 cc. autoclave, fitted with athermometer, a pressure gauge, a stirrer, a temperature control jacketand inlet valves for liquids and gases, after flushing with nitrogen,were introduced 1500 ml. of twice distilled water containing dissolvedtherein 0.75 g. of an acid of the formula and 0.050 g. of potassiumpersulfate.

The autoclave was then pressurized by introducing, by means of acompressor, C 1 until a pressure of atm. was reached, and thetemperature was then adjusted to a temperature of C., which temperaturewas maintained by the control jacket. By means of a liquid feeding pumpthere were then introduced into the autoclave 0.050 g. of Fe(NI-I (SO61-1 0 dissolved in 100 ml. of twice distilled, deaerated water.

As the reaction gradually proceeded, additional C 1 was introduced intothe autoclave so as to maintain the pressure constant at 20 atm.

After 60 minutes of reaction, the residual gases in the autoclave weredischarged into the atmosphere, the autoclave was then opened and anaqueous emulsion of polytetrafiuoroethylene was extracted therefrom.This emulsion was coagulated by stirring for 10 minutes with a propellerturning at 700 r.p.m. The coa'gulated polymer was washed with 5 litersof distilled water, separated, and dried at 120 C. for 24 hours. Itweighed 425 g.

From the polymer thus obtained, by preforming and sintering according tothe procedure of ASTM D 1457- 62T, there were obtained small discs ofsintered polymer.

The test samples obtained from these small discs, upon being subjectedto a tensile stress at 23 C., has the following characteristics:

Tensile strength: kg./cm. 240 Elongation at break percent 280 The abovedescribed sintered polymer was of a white color and was homogeneous inappearance. This example demonstrates a useful application of thebicarboxylic acids of the present invention, namely by applying theiremulsifying powers in the techniques for the emulsion polymerization offiuoroolefins. Similar results have been obtained in emulsionpolymerization tests on fiuoroolefins, by using, instead of the abovedescribed acid, the following bifunctional compounds of the presentinvention:

coon wherein m is 1, 2, 3 or 4 COOH wherein Z is 1, 2, 3 or 4 whereinboth n and l are l or 2.

This new class of perfluorinated polyethers havin'g functional groups ofa polar and hydrophilic nature at both ends of the chain, therefore finda direct application in the field of the emulsion polymerization ofvarious monomers and in particular of fiuorinated olefins, assubstitutes for the surface active products of the conventional type,that is, of those having a hydrophilic polar group at only one end ofthe chain.

EXAMPLE 16 A sample of 1 kg. of the peroxidic polyether obtained by theprocedure described in Example F was placed into a 3 liter glass flaskfitted with a mechanical stirrer, a reflux condenser and two droppingfunnels, immersed in a thermostatically stabilizable bath. One liter ofCF CICFClz and 0.1 liter of methanol were added thereto and then, withina period of about an hour, 0.4 liter of 57% H1 in water and 0.2 liter ofmethanol were introduced dropwise from the two funnels so as to maintainthe mixture at a moderate reflux.

The reaction mixture was then kept boiling gently for another 10 hours,after which the fiuorinated organic layer was separated, washed threetimes with SO -saturated water and then with water only, dried with NaSO and finally was concentrated by evaporation of the fluorinatedsolvent at C. 800 g. of a product were obtained consisting of a mixtureof diestcrs having the following formula:

CH OCOCF -O (CF 0) n -(CF CF O) CF COOCH wherein the average ratio ofthe indices l/n is about 0.75. The diester mixture had an averagemolecular weight, determined by the alkalimetric method, of 450,corresponding to an average value (n+l) of about 2.5.

A sample of 500 g. of said mixture of diesters was subjected todistillation under a vacuum of 2 mm. Hg up to a temperature of C. Aresidue was obtained of 210 g. of a mixture of diesters having anaverage molecular weight of 1950, corresponding to an average (n+1)value of about 20.

EXAMPLE l7 1 liter of CF ClCFCl 0.2 liter of 80% methanol in water and20 ml. of 57% HI in water were introduced into a 3 liter glass flask,immersed in a thermostatically stabilized bath and fitted with amechanical stirrer, a reflux condenser and a gas inlet tube reaching tothe bottom of the flask. Gaseous S was bubbled into the mixture, whichwas heated at reflux, at a flow rate between 10 and 20 liter/hr. 1 kg.of peroxidic perfluoropolyether containing 2.1% by weight of peroxidicoxygen obtained as described in Example F was added slowly over a threehour period.

The mixture was then stirred for 8 hours at a temperature of from 43-45C. and was continuously saturated with S0 The lower fluorinated layerwas then separated and washed repeatedly with water, dried with Na SOand finally was concentrated by evaporation. The residue consisted of805 g. of a mixture of the methylesters of dicarboxylicperfluoropolyetheric acids, analogous to that obtained in Example 16.

Similar results were obtained by introducing 80 g. of iron powderinstead of feeding in S0 gas.

EXAMPLE 18 A sample of 13 kg. of peroxidic perfluoropolyether containing2.1% by weight of peroxidic oxygen, prepared as described in Example F,was introduced into a 10 liter glass vessel fitted with a mechanicalstirrer, an inlet feed tube for dry nitrogen reaching to the bottom ofthe vessel, a thermometer and a gas outlet tube. The temperature of thereaction mass was brought up to 120 C. and then, over a 6 hour period,was increased slowly to 170-175 C., while the mass was continuallystirred and the gases produced, consisting mainly of C01 were vented soas to maintain constant pressure.

After an additional 4 hours at 175 C., an analysis of the product showedthat the peroxidic oxygen content had dropped to a value correspondingto 1.1% by weight. 11 kg. of product was obtained having an r/q ratio of0.75. The average molecular weight did not vary significantly from thatof the starting material.

A portion of this product was introduced into a 25 liter polypropylenereactor fitted with a mechanical stirrer, a reflux condenser, athermometer, two dropping funnels and a cooling jacket containingcirculating water at 45 C. 8 liters of CF ClCFCl and 1 liter of methanolwere added to the reactor. 3 liters of methanol and 2 liters of 57% HIin water were added dropwise at the same time over a period of threehours at such a rate as to maintain the reaction mixture at reflux.

After an additional 8 hours, the fluorinated organic layer wasseparated, washed with SO -saturated water and then with water only, anddried with Na SO The CF CICFCI solvent was removed by distillation and8.7 kg. of a mixture of dimethylesters ofpolyoxa-perfluoroalkan-dicarboxylic acids were obtained, this mixturehaving an average molecular weight of 1700, determined by saponificationwith an excess of alkali and back-titration with acid.

The N.M.R. analysis, by balancing the constituent units CF 0 and CF CF Oand the end groups OCF COOCH confirmed the average molecular weightalready determined by the alkalimetric method, and the absence ofperoxidic groups and of end groups having perfluoro alkyl character. Theaverage structure of the reduction product is thus indicated by theformula:

with an average ratio l/n of 0.7 and an average value of the sum n+l ofabout 17. The analysis showed, furthermore, that the distribution of thetwo different units in the chains was random.

A sample of kg. of the diesters was subjected to distillation in a 30plate distillation column. A fraction, corresponding to 15% by weight ofthe starting mixture, boiling at 150 C. under 10 mm. Hg, was obtained,WhlCh contained all of the possible diesters conforming to the abovereported formula, wherein the value of the sum n+l was between 0 and 3.A portion of the mixture of residual diesters from the distillation,amounting to 1 kg., was subjected to a further distillation at atemperature between 40 and 165 C. and under a vacuum of 0.01 mm. Hg. I11this way various fractions were obtained at increasing temperatures,which fractions amounted to about 35% by weight of the mixture treated.The residue from this distillation was subjected to moleculardistillation at 130 to 270 C., under a vacuum of 1 10- mm. Hg.

Table 2 shows the results from the distillation of the diester mixtureafter the removal of the initial 15% light product fraction.

A 3 gram sample of fraction N0. 2 of said table, having an averagemolecular weight of 915, was subjected to saponification for 3 hours at100 C. with 100 cc. of 2 N KOH. At then end, the solution was acidifiedwith 10 cc. of 20% H thereby obtaining the separation of a heavy organicliquid layer which was isolated. The water layer was extracted withethyl ether, which was added to the organic layer previously separated,and then the solvent was distilled, thereby obtaining a residue, forwhich the acidimetric LR. and the N.M.R. analyses agreed in assigningthe structure of free dicarboxylic acids corresponding to the startingfraction.

Thhe same process of saponification and recovery of the acids and therecognition analysis were carried out on 2 grams of fraction No. 15,having an average molecular weight of 4340.

Also in this case the structure of free dicarboxylic acids correspondingto the starting fraction was actually determined.

A 2 gram sample of fraction No. 4, having an average molecular weight of1454, was subjected to saponification with 10 cc. of normal KOH solutionfor 3 hours at C. At the end, neutralization was carried out with 7.25cc. of normal H 50 solution, using phenalphthalin, which corresponded tothe theoretical consumption of alkali for the formation of thedipotassium salt of the acids corresponding to the starting mixture offraction No. 4.

TABLE 2 Distilled fraction Number Average Fraction Distillation weightaverage, number range 0.) percent M.W, (n+1) (ll n) 7. 0 650 4. 8 0. 6980100/0.01 mm" 7. 2 915 7. 8 0. 74 100115/0.01 mm-.- 7. 5 1,215 11. 3 0.71 130/0.01 mm-.- 4. 1 1, 454 14. 1 0.69 150/0.01 mm--- 4. 0 1, 670 16.5 0. 70 150165/0.01 mm 4.0 1, 830 18. 5 0. 68 130/1X10- nun 9. 3 2,17022. 5 0. 67 /1X10 mm 5. 3 2, 480 26 0. 68 /1 10 mm. 4. 5 2, 690 28 0. 76/1X10' mm 4. 5 2, 900 31 0.66 /1X10- rnm 4.1 3, 300 35 0.75 /1X10- mm3.0 3, 530 38 0. 71 /1X10 mm 3. 1 3,870 42 0. 69 200/1X10- mm. 8. 54,140 45 0.71 210/1X1O" mm 4. 1 4,340 48 0. 64 220/1X10' mm- 3. 5 4, 76053 0. 63 230/1 )(10 mm.-- 3. 5 5, 380 60 0.65 240/1 10' mm" 2. 8 5, 74065 0. 60 250/1X10- rmn.. 2. 1 6, 300 71 0.63 270/1X10 mm 2.6 6, 900 780.64 Residue 10. 3 7, 600 85 0. 7 1

To the same solution were added 25 cc. of ethyl ether and 0.5 g. of AgNOdissolved in 2 cc. of water. The solution was then left to react for 30minutes and thereupon there was separated the ether layer, which wasevaporated to dryness, leaving behind a residue. The LR. analysisthereon showed the absence of free acid and a total metal saltformation, while at the same time the silver determination analysisshowed an Ag content that was the same as the theoretical for the totalsalt formation from the acids of the starting mixture.

EXAMPLE 19 A sample of 7 kg. of the perfluoropolyether peroxidecontaining 2.4% by weight of active oxygen, prepared as described inExample (G), was subjected to heating from 100 C. to 170 C. within aperiod of. 3 hours, and

was then maintained at 170 C. for 3 hours and 30 minutes in the vesseldescribed in Example 18.

At the end, the residual oil, 5.5 kg, showed a peroxidic oxygen contentof about 1% by weight of active oxygen, while the ratio r/ q had droppedto about 1.5.

A sample of 5 kg. of the heat treated product was introduced into acylindrical 15 liter polypropylene reactor fitted with a refluxcondenser, a mechanical stirrer, a thermometer, a dropping funnel and aninlet feed tube for gases reaching to the bottom of the reactor, as wellas with a jacket containing circulating water at 45 C.

Into this reactor were then introduced 4 liters of CF ClCFCl 2 liters of80% methanol and 0.2 liter of 57% HI in water. Thereupon, under stirringof the mass, gaseous S was bubbled into the mixture for 10 hours at aflow rate of 10 liters/ hr.

After 15 hours of reaction, the fluorinated organic layer was separatedand washed with water saturated with S0 and then with water. It was thendried on Na SO and concentrated by evaporation of the solvent. Theresidual 4.3 kg., consisting of a mixture of diesters ofp0lyoxyperfluoralkan-dicarboxylic acids, had an average molecular weightof 1600, as determined by alkalimetric titration and confirmed by N.M.R.analysis.

The N.M.R. spectrum indicated an average structure of the reductionproduct expressed by the formula:

with an average ratio of l/n of about 1.35, and an average value of thesum (n+1) of about 14.

A 4 kg. sample of the reduced product mixture was subjected todistillation, thereby separating a first 10% fraction having adistillation range from 50 to 1l0 C., under a reduced pressure of 0.2mm. Hg, and an alkalimetric average molecular weight of 570, and thenseparating a second 10% fraction having a distillation range from 110 to150 C., under a reduced pressure of from 0.2 to 0.05 mm. Hg, and anaverage molecular weight of 900, while the residue from thisdistillation had an average molecular weight of about 2300, asdetermined by the alkalimetric method.

The first fraction was then subjected to rectification in a 30 platedistillation column. Various fractions were obtained therefrom and fromeach of them were isolated by gas-chromatography some diesters with apurity between 97% and 99%, amongst which there were:

1 o (GFzCO o cum (2 a) 2 o F2OC FgO-C F200 0 era 12 g.)

3 o F20-C2F40-C Pic coon,

b0 0 CH3 15 g.)

4 CF -O(C F O)zCF2COOCHs c0 0 CH3 CF20O rioczrioo F20 0 0 on:

0 0 on: (a g 3 gram samples of the discarboxylic esters indicated by thenumbers 2, 3, 4 and 5, were saponified with 20cc. of 2 normal NaOH at100 C. for 3 hours. At the end, acidification was carried out with 5 cc.of 20% H 50 and the samples were then extracted twice with 10 cc. ofethyl ether. The ether layers were dried on Na SO and the solvent wasevaporated, thereby obtaining as residues the following products in thecorresponding sequence 0 Fz-O-C FgO-C F200 OH melting point 45 C. (1.5g.) (100E OFz0OzF-10CFZCOOH melting point 66 C. (1.9 g.) (30 OHCF3O(C2F40)2C FzCOOH melting point 61 C. (2.1 g.)

COOH

OF OCF 0CzF4O-CF2C0OH boiling temp. 135-137 C.

under 0.05 mm. Hg COOH (2.5 g.)

Acidimetric, N.M.R. and IR analyses confirmed the structure of the abovereported acids.

A 3 g. sample of the dimethyl ester of 3,6-dioxa-perfluorosuberic acidwas dissolved in 10 cc. of anhydrous ethyl ether and was then cooleddown to 0 C. By treating this solution gently with gaseous anhydrous NHthere was obtained a precipitate which was filtered from the ether, andwashed with ethyl ether, and which had a melting point of 170 C. The IRspectrum and the N.M.R. spectrum were in accordance with the formula:

A 2 gram sample of 3,5,8-trioxa-perfluoro-sebacic acid was treated with2 cc. of SOCl at reflux temperature, in the presence of 0.1 cc. ofpyridine. After 5 hours of reaction, the thionyl chloride was removed bydistillation and there were obtained 1.5 g. of a product which was againdistilled, thereby separating 1 gram of a fraction having a boilingpoint of 162-164 C. (750 mm. Hg), for which the acidirnetric andchlorides analyses as well as the LR. and N.M.R. spectra confirmed thestructure according to the formula:

A gram sample of the second distillation fraction of the reduced productmixture, having a distillation range between and C. under a reducedpressure of 0.20.05 mm. Hg and an average molecular and an averagemolecular weight of 900, was dissolved in 200 cc. of ethyl ether andthen treated at 0 C. with anhydrous NH When, after two hours, no furtherabsorption of ammonia could be observed, the ether and the alcoholformed in the reaction were evaporated. IR analysis confirmed that theresidue had been completely converted into the diamide.

To this residue 90 g. of P 0 were added and the mixture was thoroughlymixed and then gradually heated up to 150-200 C. for 5 hours. At theend, a reduced pressure of 0.02 mm. Hg was applied and a liquid wasdistilled at a temperature between 100 and C.

80 grams of liquid were collected on which N.M.R. analysis determinedthe presence of CF O- and C F.,O units as well as of the ()CF (CN)terminal groups, while analysis of the IR spectrum showed the presenceabsorption bands corresponding to the nitrile group in the 2.250 cm.zone and the absence of those of the amide group in the zones 1.7001.720crnf and 1.6201.630 cmr Variations can, of course, be made withoutdeparting from the spirit and scope of the invention.

Having thus described our invention, what we desire to secure and claimby Letters Patent is:

1. Bifunctional perfiuorinated polyethers and mixtures thereof, havingchemically reactive terminal groups at both ends of the chain, saidpolyethers having from 1 to 100 repeating units selected from the groupconsisting of C3F50, --C2F40-, and CF O, WhCI'ein CgFs and C 1 areperfiuoroalkylene units derived from the opening of the double bond of ahexafiuoropropylene and of a tetrafiuoroethylene molecule, respectively,the different oxyperfiuoroalkylene units having a random distributionalong the chain, there being no more than 50 of any one of said speciesof repeating units, said CF O repeating units being present only wheneither or both of said C F O- and C F O- repeating units are present,said --C F O units being present only when said -CF O- units are alsopresent, said C F O- units being present only when either said CF Ounits are also present or when said polyether contains a terminal groupbonded to said chain through an ether oxygen, said polyether havingterminal groups bonded to said chain through an ether oxygen, saidterminal groups being selected from the group consisting of at least oneof the latter two terminal groups being present when C F O repeatingunits are present, with the further proviso that when said CF CO+CFterminal group is present, one of said other two terminal groups is alsopresent, and the corresponding acyl halides, lower alkyl esters andmetal salts.

2. The perfluorinated mixtures of polyethers of claim 1 having from 1 to50 CF O units, from 1 to 50 C F O units, no -C F O units and a total ofbetween 2 and 85 repeating units, the average ratio of C F O units to CFO-- units being from about 0.2 to about 5, and their correspondingacyldihalides, lower alkyl diesters, and di-metal salts.

3. The perfiuorinated mixtures of polyethers of claim 2, wherein theaverage ratio of C F O units to units is from about 0.5 to about 1.5.

4. The perfiuorinated polyethers of claim 1 having from 1 to 5 -CF Ounits and from 1 to 5 C F O units.

5. The polyethers of claim 1 wherein the total number of repeating unitsis between 1 and 85.

6. The polyethers of claim 5 wherein the total number of repeating unitsis between 1 and 50.

7. The perfiuorinated polyethers of claim 1 having the formula wherein mis an integer from 1 to 4.

8. A process for preparing bifunctional perfluorinated ether polymersand mixtures thereof, having chemically reactive terminal groups at bothends of the chain, said ether polymers having from 0 to 100 repeatingunits selected from the group consisting of C F O,

and CF O, wherein C 1 and C 1 are perfiuoroalkylene units derived fromthe opening of the double bond of a hexafluoropropylene and of atetrafiuoroethylene molecule, respectively, the diiferentoxyperfluoroalkylene units having a random distribution along the chain,there being no more than 50 of any one of said species of repeatingunits, said ether polymer having terminal groups bonded to said chainthrough an ether oxygen, said terminal groups being selected from thegroup consisting of said latter two terminal groups being present onlywhen said C F Orepeating units are present and both said latter twoterminal groups being present when only -C F O- units are present, withthe further proviso that when said CF COCF terminal group is present,one of said other two terminal groups is also present, and thecorresponding acyl halides, esters and metal salts, said processcomprising reacting a reducing agent, at a temperature of from about -30C. to 250 C., under a pressure between about 1 and 200 atmospheres, inthe presence or absence of a solvent or a dispersing agent, with aperfiuorinated linear polyether containing peroxidic oxygen bridges, ora mixture of said polyethers, said peroxidic oxygen-containing polyetherhaving at least about 10 repeating units selected from the groupconsisting of -C F O--, C F O-, and CF O-, wherein C F and C F areperfluoroalkylene units derived from the opening of the double bond of ahexafluoropropylene and of a tetrafiuoroethylene molecule, respectively,said repeating units being randomly distributed along the chain andlinked one to another either directly or through an oxygen atom wherebya peroxy group is present at random along the chain, there being no morethan 100 of any one of said species of repeating units and from 1 to ofsaid randomly distributed peroxy groups in said chain, the ratio of thetotal peroxy groups to the sum of the total C F O units plus total C F Ounits plus total CF O- units being between about 0.01 and 0.9, the sumof the total C F O units plus total C F O units being greater than thetotal number of peroxy groups, said polyether having terminal groupsbonded to said chain through an ether oxygen, said terminal groups beingselected from the group consisting of CF;;, CF3O-CF, COF, CF2COF,-CF-COF,

and CF2CO-CF3, and their corresponding acyl halides, esters and metalsalts; said reducing agent being selected from the group consisting ofmolecular hydrogen; nascent hydrogen; primary and secondary alcoholsalone or in the presence of aluminum alcoholates; simple hydrides; boronand aluminum complex hydrides; sulfur dioxide, hydrogen sulfide and thealkali metal salts thereof; hydrazine; hydroxylamine; phosphorous acid,hypophosphorous acid and the alkali metal salts thereof; iron; tin;stannous chloride; hydroiodic acid, and a complex reducing agent formedby a mixture of 57% aqueous hydroiodic acid with iron or gaseous S0 9.The process of claim 8 wherein the reaction product comprises at leastone linear polyether having the formula wherein m is an integer from 1to 10, said starting peroxidic polyether having only C F O repeatingunits and a ratio of peroxy groups to C F O repeating units betweenabout 0.01 and 0.9.

10. The process of claim 8 wherein the reaction product comprises atleast one linear polyether having both C F O and CF O- repeating unitswherein the ratio of the total CF O- repeating units plus one to thetotal C F O repeating units plus one is from about 0.16 to 6, saidstarting peroxidic polyether containing both CF O and C F O- repeatingunits, the ratio of the total CF O units to the total C F O units beingfrom 0.1 to 100, and the terminal groups being selected from the groupconsisting of CF -COF and -CF COF.

11. The process of claim 8 wherein the total number of repeating unitsin said peroxidic oxygen-containing polyether is between about 10 and100.

12. The process of claim 8 wherein the ratio of the total number ofperoxy groups to the total number of repeating units in said peroxidicoxygen-containing polyether is between about 0.1 and 0.5.

13. The process of claim 8 wherein said reaction temperature is betweenabout 20 and C.

14. The process of claim 8 wherein said reaction pressure is betweenabout 1 and 100 atmospheres.

15. The process of claim 8 wherein said reduction reaction is carriedout in the presence of a solvent or dispersing agent which is inerttowards the reactants used and towards the terminal group C F COO F 0 Fand -0 F-COF.

16. The process of claim 15 wherein said starting peroxidic polyethercontains at least one terminal group CF -COCF or at least oneperfiuoropropylene unit adjacent to a peroxidic bridge and linked to itby the polyether reaction product has one F-COF GEa terminal group, theremaining terminal groups being selected from the group consisting of CFCOCF and CF COF.

18. The process of claim 15 wherein said starting peroxidic polyetherconsists of a polyether in which there is no C F O repeating unit andwherein there is no CF COCF terminal group, whereby said bifunctionalperfluorinated ether polymer product comprises at least one polyethercontaining a CF COF terminal group.

19. The process of claim wherein said solvent or dispersing agent isselected from the group consisting of hydrocarbons, chlorinatedhydrocarbons, chlorofiuorinated hydrocarbons, fluorinated andperfluorinatecl hydro carbons, and linear and cyclic ethers and theirperfluorinated derivatives.

20. The process of claim 8 wherein said reducing agent is molecularhydrogen in the presence of an hydrogenation catalyst selected from thegroup consisting of palladium, platinum and nickel in the form of metalin a finely subdivided state or supported on carbon or alumina, saidreaction temperature is from about 0 C. to 200 C.

23 and said reaction pressure is from about 1 to 200 atmospheres.

21. The process of claim 20 wherein said reaction temperature is fromabout 20 C. to C.

22. The process of claim 20 wherein said reaction pressure is from about5 to 100 atmospheres.

23. The process of claim 8 wherein said reducing agent is hydriodic acidin the presence of a liquid selected from the group consisting of water,acetic anhydride, methanol, ethanol, trifiuorotrichloroethane andmixtures thereof.

24. The process of claim 8 wherein said reducing agent is formed by amixture of 57% aqueous HI with gaseous S0 and the reaction is carriedout in the presence of a solvent mixture consisting of methyl alcoholand CF Cl--CFC1 25. The process of claim 8 wherein said reducing agentis formed by mixture of 57% HI with iron and the reaction is carried outin the presence of a solvent mixture consisting of methyl alcohol and cFClCFCl References Cited UNITED STATES PATENTS 3,250,806 5/1966 Warnell260--535 H 3,442,942 S/l969 Liances et a1 260535 H FOREIGN PATENTS6504428 10/1965 Netherlands 260535 H LORRAINE A. WEINBERGER, PrimaryExaminer P. J. KILLOS, Assistant Examiner US. Cl. X.R.

260-322, 32.4, 78 R, 78.3 R, 348.5 R, 465.6, 483, 484 R, 484 P, 496, 535P, 544 Y, 544 F, 561 HL, 594, 610 B, 615 BF 0 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent No. 3,847,978 Q Dated November12 1974 DARIO SIANESI GERARDO CAPORICCIO DOMENTCO MENSI Inventor(s) Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 25 lines 9--ll:

"-CF COOH -C-CFCOOH, and "CF -CO-CF and CF COCF should read -CF COOH,-cF ooH, and CF -COCF a CF 3 Signed and Scaled this twenty-third 0fMarch 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Alresting Officer Commissioner nfParenlsand Trademarks Q

1. BIFUNCTIONAL PERFLUORINATED POLYETHERS AND MIXTURES THEREOF, HAVINGCHEMICALLY REACTIVE TERMINAL GROUPS AT BOTH ENDS OF THE CHAIN, SAIDPOLYETHER HAVING 1 FROM 1 TO 100 REPEAING UNITS SELECTED FROM THE GROUPCONSISTING OF -C3F6O-, -C2F4O-, AND -CF2O-, WHREIN C2F6 AND C2F4 AREPERFLUOROALKYLENE UNITS DERIVED FROM THE OPENING OF THE DOUBLE BOND OF AHEXAFLUOROPROPYLENE AND OF A TETRAFLUOROETHYLENE MOLECULE, RESPECTIVELY,THE DIFFERENT OXYPERFLUOROALKYLENE UNITS HAVING A RANDOM DISTRIBUTIONALONG THE CHAIN, THERE BEING NO MORE THAN 50 OFF ANY ONE OF SAID SPECIESOF REPATING UNITS, SAID -CF2OREPEATING UNITS BEING PRESENT ONLY WHENEITHER OR BOTH OF SAID -C2FF4O- AND C3F6O- REPEATING UNITS ARE PRESENT,SAID -C2F4O -UNITS BEING PRESENT ONLY WHEN SAID -CF2O- UNITS ARE ALSOPRESENT, SAID C3F6O- UNITS BEING PRESENT ONLY WHEN EITHER SAID -CF2O-UNITS ARE ALSO PRESENT OR WHEN SAID POLYETHER CONTAINS A